In the current market of computer printers, ink-jet printers are relatively inexpensive in terms of good quality they offer. Compared with laser printers, each type of printers has its respective strengths and weaknesses. The ink-jet printers are lower priced but cost more in printing. The laser printers are more expensive, but cost less in printing. Therefore, for the ink-jet printers, the goal of lowering printing cost for greater competitiveness becomes a pressing task for further research and development.
Any ink-jet printing technology generally includes controlling devices for releasing ink to a printing surface. Regarding a ink-jet printing technology in the prior art, a printhead is fitted to a ink-jet cartridge, which releases ink jets in response to control signals.
Two methods, thermal-bubble and piezoelectricity methods, are generally employed by the printhead for releasing ink jets. In the thermal-bubble method, the printhead employs a membrane resistor that heats up small portion of ink (ink droplets) to gaseous state rapidly for releasing in jets through the nozzle.
In the piezoelectricity method, the printhead employs a piezoelectric element that compresses the volume of the ink in response to control signals for creating pressure waves and then forcing the ink droplets in jet though the nozzle.
One type of printheads for thermal-bubble ink-jet printers has been disclosed in the prior art, which is a layer structure manufactured via the VLSI manufacturing process, such as the layer structure disclosed in the U.S. Pat. No. 4,513,298. This layer structure is a three-dimensional structure gradually formed via multiple manufacturing steps. FIG. 1 shows the plane elevated view of the printhead layer structure. The nozzle plate is removed in FIG. 1 for clear illustration of the layer structure. As shown in FIG. 1, the components of the printhead includes at least the followings in proper order from the bottom to the top: a base layer 11, a pattern layer 12 and a dry film of a channel barrier layer 13. This structure is manufactured via the VLSI manufacturing process with add-in silicon chips. The topmost layer of the dry film of the channel barrier layer 13 is represented by dotted lines in FIG. 1. FIGS. 2 and 3 illustrate the printhead structure and mechanism. FIG. 2 is a close-up view of the nozzle cavity and FIG. 3 is a cross-sectional view of the nozzle cavity which shows the layer structure of one nozzle cavity. The dry film of the channel barrier layer 13 shown in FIG. 1 is situated on the top of the pattern layer 12 and forms an ink channel 131 in the center of the channel barrier layer 13 and a plurality of ink cavities 132 on the two sides of the ink channel 131.
As shown in FIG. 2, an ink first flows, via an ink cartridge (not shown), into an ink channel 131 and then into each ink cavity 132. Referring to FIG. 3, where the nozzle plate 14 and the dry film of a channel barrier layer 13 are thermally compressed together for tight adhesion. The nozzle plate 14 has a plurality of openings corresponding to each ink cavity 132. With ink flowed into it, the ink of each nozzle cavity 132 is heated up by the heating layer 121 of the pattern layer 12 in response to the control signals from the printer, so that the ink expands in volume and is jetted out through the openings of the nozzle plate 14.
FIG. 3 further illustrates the layer structure of the printhead in which the base layer 11 includes a silicon base layer 111 and a silicon dioxide layer 112 for forming the base of the printhead, and the pattern layer 12 includes a heating layer 121, a first passivation layer 122 and a second passivation layer 123 for forming the ink-heating structure for the printhead.
FIG. 4 is a cross-sectional view along the Axe2x80x94A line of the printhead shown in FIG. 1. It can be seen that when the pattern layer 12 is formed on the two sides of the ink channel 131, there emerges a height differential (about 0.6 xcexcm) between the pattern layer 12 and the gap which is formed at the ends of the ink channel 131 because there is none pattern layer 12 arranged on the two opposite ends of the ink channel 131. Hence as the dry film of channel barrier layer 13 is formed on its top, a step differential d of about 0.6 xcexcm is created at the ink channel 131. When adhering nozzle plate 14 (usually made of nickel) onto the dry film of a channel barrier layer 13 (usually high polymer compound of Morton, Vacrel or the likes), high temperature at 120xc2x0 C. and high pressure are needed for 2 to 5 minutes for the high polymer to combine with the nozzle plate 1.
Referring to FIG. 4 again, as the nozzle plate 14 is thermally pressed along the directions pointed by the arrows for adhesion with the dry film of the channel barrier layer 13, a greater pressure is required to deform the dry film of channel barrier layer 13, so that it pushes and squeezes the ink channel 131 for closing up gaps created by the step differential d for preventing the ink leakage though such gaps.
However, the great tangential shear force B, generated by the great pressure due to the thermal compression of FIG. 4, may cause the dry film of the channel barrier 13 in each ink cavity 132 to be deformed transversely so that it leads to reduce internal volume and raises higher printhead ill rates. Generally, the tolerable error for the size of the ink cavity 132 is within +/xe2x88x9210xcexc. If the thermal pressure is too high, the ill rate will increase.
As the step differential d of pattern layer 12 is responsible for causing in the compression process of the nozzle plate 14, the primary object of the present invention is to provide a manufacturing method for the printhead and the structure thereof, which can reduce the differential on the two opposite ends of ink channel 131, so that the dry film of channel barrier layer 13 is made smoother, and the nozzle plate 14 can adhere tightly with the dry film of channel barrier layer 131 for eliminating the ink leakage problem.
It is an object of the present invention to provide a structure of a printhead for raising its product acceptance rate and improving its quality.
According to the present invention, a structure of a printhead, including a base layer, a pattern layer disposed on the base layer and having a flow pattern disposed on two opposite ends of the base layer and having a space location for forming thereabove a flow channel, and a base pattern disposed on two opposite sides of the base layer and having plural apertures for forming thereabove plural ink cavities, wherein the flow pattern and the base pattern surround a central location for forming thereabove an ink channel, the base pattern includes at least a heating layer and a passivation layer, and the flow pattern is made of the same material and at the same height as those of the base pattern, a channel barrier layer disposed on the pattern layer and having a dry film, the ink channel, the flow channel and the plural ink cavities, and a nozzle plate adhered to the dry film of the channel barrier layer, wherein the nozzle plate has plural ink openings disposed over the ink cavities.
Certainly, the nozzle plate can be adhered to the dry film of the channel barrier layer by thermal compression.
Certainly, the pattern layer can be made by means of a semi-conductor manufacturing process.
Certainly, the heating layer can be made of tantalic aluminum (TaAl).
Certainly, the first passivation can be made of one of silicon nitride (Si3N4) and silicon carbide (SiC).
Certainly, the second passivation can be made of tantalum (Ta).
Certainly, the nozzle plate can be made of nickel (Ni).
Preferably, the base pattern and the flow pattern are in discontinuously alternate arrays.
Preferably, the flow pattern incluses a first flow pattern and a second flow pattern disposed in discontinuously arrays for forming thereabove a flow channel.
Preferably, the flow pattern is formed by a first flow pattern and a second flow pattern disposed in discontinuously arrays for forming thereabove the flow channel.
Preferably, the first passivation layer and the second passivation layer of the pattern layer are continuous and formed in the same shape and the heating layer of the pattern layer is a discontinuous array.
According to the present invention, a structure of a printhead including a base layer, a pattern layer disposed on the base layer and having a flow pattern disposed on two opposite ends of the base layer and having a space location for forming thereabove a flow channel and a base pattern disposed on two opposite sides of the base layer and having plural apertures for forming thereabove plural ink cavities, wherein the flow pattern and the base pattern surround a central location for forming thereabove an ink channel, the flow pattern includes a first flow pattern and a second flow pattern disposed in discontinuously arrays and forming a flow channel, a channel barrier layer having a dry film and the ink channel, and a nozzle plate adhered to the dry film of the channel barrier layer.
According to the present invention, a structure of a printhead, including a base layer, a pattern layer disposed on the base layer and having a flow pattern disposed on two opposite ends of the base layer and having a space location for forming thereabove a flow channel and a base pattern disposed on two opposite sides of the base layer and having plural apertures for forming thereabove plural ink cavities, wherein the flow pattern and the base pattern surround a central location for forming thereabove an ink channel, a channel barrier layer disposed on the pattern layer and having a dry film, the ink channel, the flow channel and the plural ink cavities, and a nozzle plate adhered to the dry film of the channel barrier layer, wherein the nozzle plate has plural ink openings disposed over the ink cavities.
Now the foregoing and other features and advantages of the present invention will be more clearly understood through the following descriptions with reference to the drawings, wherein: